P5 â€“ Energy Costs By the end of this topic I will be able to: q Calculate the amount of energy transferred from the mains. q Calculate the cost of energy transferred from the mains. q Understand that the amount of electrical energy a device transforms depends on how long the q q q q
appliance is switched on and the rate at which the device transforms energy. Know that the power of an appliance is measured in watts (W) or kilowatts (kW). Know that energy is normally measured in joules (J). Know that the eelectricity is transferred To your house from The power station along the National Grid. Understand why the National Grid uses of step-up transformers to increase voltage (potential difference) and reduces current( to reduces energy losses in the cables) from power station to national grid. Understand why the National Grid uses of step-down transformers to decrease voltage (potential difference) and increase current( for safety) from national grid to your home.